Shailene Woodley recently revealed the changes she had to undergo in the physical transformation to play Hazel Grace Lancaster in The Fault in Our Stars, in comparison to her role as Tris in Divergent. Shailene said she had to change her body in a way that portrayed a young woman who is very sick and wouldn't have muscles like a Dauntless inititate. Read more about it below in an interview with Entertainment Weekly:

“I didn’t have to change much in terms of eating or exercise or anything to do Divergent,” Woodley said. “I had to do much more in terms of physical transformation for Hazel in Fault In Our Stars. Especially going from Tris with strong muscles and long hair to Hazel, who is sick and weak and in a very hard and sad situation. The messages are so important in Fault. I can’t wait for people to see it. I feel so honored to be a small part of that movie. I know that sounds cliché, but it is true. The demographic is unlimited. It has the potential to reach so many people.”